The growth in the use of reinforced plastics since World War II has been phenomenal. Materials falling in this category are to be found in industrial equipment, in consumer products, in military devices and in space equipment. Reinforced plastics are now classed as very important materials of construction which figure prominently in the nation's economy. Reinforced plastics have been in use in flight vehicles since the days of doped muslin. At the present time, metal, glass-fiber, and ceramic reinforced plastics are widely used in aircraft. Of particular importance is the widespread use of boroaluminosilicate fibrous glass-reinforced plastics in devices such as radomes, airframes, structural accessories, compressed gas containers, engine housings, helicopter rotor blades, helmets, and many others. Asbestos and aluminum silicate fibers are also employed. Special fibers and resins having higher modulus of elasticity, lower dielectric constant and loss factor, greater strength at normal and elevated temperatures, greater weather resistance, and other special properties are under development. As these improved materials become available commercially, it is expected there will be further exploitation of reinforced plastics in aircraft. Reinforced plastics have been in use in rockets since the invention of rolled paper casings for fireworks. Of great current importance and interest is the fact that the feasibility has been firmly established for the use of boroaluminosilicate fibrous glass-reinforced plastics in the construction of high-pressure solid-propellant motor casings for large rockets. Many final stage rocket motors made of isotensoid-wound glass-roving reinforced plastics have been flown successfully in the exploration of space. No operational failures of these casings have been reported to date. The majority of spent motors still in orbit are made of reinforced plastics.